A DeltaVision Optical Sectioning (deconvolution) microscope system and SGI workstation are requested by a group of four major users and a community of minor users at the University of California, Berkeley. Currently, there is no instrument of this kind at UC Berkeley. Projects include studies of chromosome arrangement in meiosis, retinal degeneration, secretion in gastric parietal cells, chromatin associated proteins and sex chromosome inactivation. All users have current NIH funding. Two of the investigators have extensive experience with this instrument and the other two investigators have used deconvolution microscopy in their research. Images are recorded on a cooled CCD (charged-coupled device) camera that has both high resolution and low light level sensitivity. Filter combinations, motorized control of the microscope stage (X, Y & Z directions), lamp and CCD Shutters, and CCD data collection are all computer controlled and coupled to a Silicon Graphics display system. The DeltaVision system is ideal for any imaging where low light levels are critical. This is very important in looking at living cells since long term exposure to high light intensities bleach dyes and damage the specimen. It is also useful when a specimen is stained with multiple probes, and some of them are easily bleached. Three dimensional deconvolution programs will give high resolution three dimensional images equivalent or better than that achieved using confocal microscopy. A software package for image analysis and volume rendering, including stereographic viewing is integral to the system and is much more useful than the image analysis packages sold with confocal microscopes. The DeltaVision system uses a UV light source with a continuous emission spectrum permitting several fluorescent probes to be monitored simultaneously. The microscope will be placed at a shared use site in the Life Sciences Addition building, Department of Molecular and Cell Biology, UC Berkeley. The instrument will be under the supervision of a trained Staff Research Associate.